The present invention relates generally to a method for cohesively bonding metal to a non-metallic substrate and more particularly, to the use of metallic micro and nano size filaments, embedded within the non-metallic material, to create cohesive bonds with the metallic material.
Non-metallic materials, and in particular composite materials such as graphite-fibers or fiberglass fibers with epoxy matrices, are notoriously difficult to attach to metallic materials. The most commonly used methods to create such assemblies are adhesive bonding or the use of fastening devices. Both of these methods have disadvantages related to disbonding due to water infiltration and corrosion or due to the fracture of the superficial surfaces where the fastening devices are connected to the composite material.
Various methods are commonly used to attach two metal surfaces to each other. Besides fastening, welding is such a method; however, many others such as brazing, soldering, diffusion bonding and adhesive bonding are widely used in industry. All of these methods are generally dependent upon a plurality of parameters including applied pressure, bonding temperature, time, and the method of heat application. The surface finish of the components can play an important role, as well. To form a cohesive bond, it is important for two, clean and flat surfaces to come into atomic contact with one another, with microasperities and surface layer contaminants being removed from the bonding faces before bonding.
Welding, in general, is making use of high temperatures to melt the two metals in contact with each other or to melt a filler material, creating a pool of common, molten alloy that when solidified, would strongly connect the two together. On the other side, the diffusion bonding process is known to create a strong bond between two metals without melting them by using only pressure and lower temperatures, and without the introduction of any extrinsic material.
However, bonding a metal surface to a non-metallic substrate generally cannot be accomplished by any of the methods outlined above and often requires the addition of an extrinsic material, such as an adhesive. Hence, adhesive bonding or fastening methods are extensively used to connect metallic materials to non-metallic substrates.
Accordingly, it would be desirable to have a bonding method that forms a strong cohesive bond between a metal body and a non-metallic substrate.